This invention related to a process for the production of a stable polyol-oxidated silicon-acidic Boron emulsion. This stable emulsion and or suspension is produced by mixing a hydrated or dry powdered oxidated silicon compound and a powdered acidic boron compound in a liquid polyol. I have discovered that when boric acid is mixed with an alkali silicate compound in a polyol most of the boric acid remains as boric acid and functions as a very good flame-retardant in the production of polyurethane foamed products.
Organic-inorganic emulsions and suspension, were produced in U.S. Pat. Nos. 4,743,624; 4,737,525; 4,778,844; 4,282,429; 4,325,859; 4,376,178; 4,296,211 and Re. 31,340 by utilizing a thixotropic agent, in the form of a silicate, to stabilize the emulsion. In this invention an acidic boron compound is added to produce a flame-retardant product. The addition of boric acid greatly improves the flame-retardant properties of products such as polyester silicate resins, polyesteramide silicate resins and polyurethane silicate products. It is known in the arts that salts of boric acid are not very useful as a flame-retardant because other flame-retardants must be added with them to be useful. In the novel process of this invention only a small amount of acid boron compounds are necessary to produce a flame-retardant product because the molecules of the boric acid are well distributed throughout the product. In the process of this invention, low cost and readily available compounds are utilized and there is an improvement in the cost of the product, in the amount of flame-retardant needed, an in the production of inexpensive flame-retardant compounds.
When the flame-retardant emulsions of this invention is to be used in the production of polyurethane silicate products, it is necessary to utilize a basic compound such as alkali metal silicate and alkaline earth metal silicates to adjust the pH. Boric acid is a reaction retarder and slows the chemical reaction therefore a satisfactory polyurethane silicate foam can not be produced unless the pH is elevated. to above a pH of 6, preferably to a pH of 7 or above. The pH is elevated by adding a basic compound to the emulsion or mixture of the components. It is preferable that the basic compound does not react with the acid boron compound but in most of the mixtures of components some chemical reaction takes place between them. When they react together only a minimum amount of the basic compound should be used because the acid boron compound is a much better flame-retardant than the salt of acid boron compound. A combination of a basic oxidated silicon compound which react very little with the acid boron compound may be used so that free acid boron compound may be present in the emulsion or reaction mixture.
While not wishing to be bound by any theory of operation, it appears that there is some reaction of the acidic boron compounds with the oxidated silicon compound and polyol to give a much better and more stable distribution of oxidated silicon powder and acidic boron compound powder in the liquid polyol. This combination of well distributed particles of oxidated silicon compound and acidic boron compounds gives good flame-retardant properties to the emulsion and the products produced from the emulsion. Any excess of oxidated silicon compounds may be used as a filler. The combination of oxidated silicon powder and acidic boron compound powder enhances the flame-retardant emulsion of this invention is reacted with a polyisocyanate there is a chemical reaction between the polyisocyanate and the polyol, oxidated silicon compound and acidic boron compound. Excess acidic boron compounds may be used and acts as a flame-retardant filler. The boric acid may also be esterified with the polyol by heating.